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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Comparing CO2 emissions to CO2 levels

What the science says...

When CO2 emissions are compared directly to CO2 levels, there is a strong correlation in the long term trends. This is independently confirmed by carbon isotopes which find the falling ratio of C13/C12 correlates well with fossil fuel emissions.

Climate Myth...

CO2 emissions do not correlate with CO2 concentration
'It is easily demonstrated that there is no correlation between CO2 emissions and atmospheric CO2 concentration. Over the three years from 1979 to 1982 when CO2 emissions were decreasing due to the rapid increase in the price of oil that drastically reduced consumption, there was no change in the rate of increase in atmospheric concentration of CO2 proving that humans were not the primary source for the increase in concentration.' (Telegraph)

To directly compare CO2 emissions to atmospheric CO2 levels, both sets of data can be converted to gigatonnes of CO2. The CO2 emissions data is typically expressed in gigatonnes carbon (GtC). One gigatonne is equal to one billion tonnes. This means they've only included the carbon element of the carbon dioxide molecule. The atomic mass of carbon is 12, while the atomic mass of CO2 is 44. Therefore, to convert from gigatonnes carbon to gigatonnes of carbon dioxide, you simply multiply 44 over 12. In other words, 1 gigatonne of carbon equals 3.67 gigatonnes of carbon dioxide.

Atmospheric CO2 levels are expressed in parts per million by volume (ppm). To convert from ppm to gigatonne of carbon, the conversion tables of the Carbon Dioxide Information Analysis Center advise that 1 part per million of atmospheric CO2 is equivalent to 2.13 Gigatonnes Carbon. Using our 44 over 12 rule, this means 1ppm = 7.81 Gigatonnes of Carbon Dioxide. Thus the two time series can both be plotted together expressed as gigatonnes of carbon dioxide:

So putting it all together, Figure 1 is a plot of the total amount of CO2 in the atmosphere (top) versus the total amount of CO2 humans have emitted into the atmosphere (bottom). Several features jump out. Firstly, the similar shape of the curves (dare I say hockey stick shaped). We have correlation but do we have causality?

It isn't too much of a stretch to imagine the amount of CO2 we put into the atmosphere might have a causality link with the amount of CO2 that remains in the atmosphere. Nevertheless, further confirmation comes by analysing the types of CO2 found in the air. The carbon atom has several different isotopes (eg - different number of neutrons). Carbon 12 has 6 neutrons, carbon 13 has 7 neutrons. Plants have a lower C13/C12 ratio than in the atmosphere. If rising atmospheric CO2 comes fossil fuels, the C13/C12 should be falling. Indeed this is what is occuring (Ghosh 2003) and the trend correlates with the trend in global emissions.

Comments

The rate of increase of CO2 levels had changed of course even in 1979 to 1982. It fluctuates a lot all the time, as visible from Mauna Loa or global data. This is due to due to the changing fluxes between atmosphere and other pools. A minor signal of yearly variability of human-emitted CO2 is scarcely detectable. A historic discussion of variability of concentration rise is within the Charles D. Keeling autobiography Rewards and penalties of monitoring the Earth from 1998. Excellent images on CO2, fossil fuels and the influences onto CO2 rise anomalies are within his 2005 Tyler Prize Presentation.

A minor correction: Law Dome data have 2455 in its URL (the link within the text pointed to Tayler Dome, 2419).

I find this one bit hard. While I can accept what is written above, I come unstuck when comparing it all with what is written at: https://chiefio.wordpress.com/2009/02/25/the-trouble-with-c12-c13-ratios/

Worse, the arguments are not quantified (i.e. are little more than handwaving).

Worse still, they are accompanied by the Usual Suspects -— a grabbag of run-of-the-mill anti-science nonsense arguments, all long-debunked but living a zombie-like undead existence on Denialist websites.

[ The author himself claims to be a frequent contributing author at WUWT. My apologies, if that is taken as an Ad Hominem ! ;-) ]

All in all, chiefio-wordpress is a waste of readers' time.

Sorry for the harsh review, Patrick. "Chiefio" was a waste of your time, too.

Chiefio restates questions as problems when the answers are well knows. For example, he questions wether we know the ratio of C12/13 at midocean ridges. Seems like a good question since the mid-ocean ridges are underwater. Except Iceland is a midocean ridge with many active volcanoes so this ratio has been measured. Undoubtedly scientists have also measured this ratio for other mid-ocean ridges.

This is not an issue of scientists not knowing the answers but Chiefio has made no effort to find the answers to the questions he asks. There is probably a lot of Chiefio ignoring the answers when they are provided to him.

It is easy to make any problem look hard if you ignore the answers scientists have found.